1. Field of the Invention
The present invention relates to the detection and evaluation of the freshness or the extent of degradation or spoilage of a protein based product, as an indication of the degree of the quality of the protein based product.
2. Description of the Related Art
Traditional methods for evaluating the freshness or degree of spoilage of fish include sensory evaluation (appearance, feel, and smell). This method is subjective and debatable.
U.S. Pat. No. 5,744,321 discloses a colorimetric method for rapidly evaluating the degree of bacterial degradation of fish, such as codfish, catfish, and winter flounder, by mixing the fish flesh with a bacterial nutrient broth, and reacting the extract with a water-soluble chromogen such as an ionized tetrazolium dye salt which undergoes a reduction reaction with the fish bacteria to produce a water-insoluble formazan dye or colored reaction product. Next, a surface active agent is added to help solubilize the formed formazan dye, and produce lysis and stop the reaction, and an aliphatic alcohol solvent is added to dissolve the formed formazan dye or colored reaction product, and prevent further breakdown and darkening with time. The dissolved reaction product has a color which is intensified depending upon the bacterial population of the fish sample and which can be evaluated calorimetrically by visual comparison with a standard color chart indicative of low, medium and high bacterial populations. This method is complicated because it involves quite a few steps and reagents.
Therefore, there is still a need to provide an accurate, convenient, and objective method of evaluating the freshness of a fish product for fish purveyors, restaurants, hospitality companies, and food service companies, etc.